The present invention relates to a composite tubing for use in a variety of applications and a method for manufacturing the invention. The present invention pertains to a flexible and reinforced tubing which can transmit rotational (i.e. torque) and translational (i.e. push-pull) motion. In additional, the present invention pertains to a method for manufacturing the reinforced and flexible invention. The present invention is particularly, through not exclusively, useful as a reinforced and flexible tube for use in medical applications such as a guiding catheter or a catheter with preferred torque, flexibility and pushable characteristics.
A large number of reinforced tubing devices have been introduced for use in a wide variety of applications. For example, flexible reinforced tubing is commonly used to transmit translational motion (i.e., push-pull) or rotational motion (i.e., torque) from a control apparatus to an object located distally which is to be manipulated or moved. An example of one such device is the reinforced tubing disclosed in U.S. Pat. No. 5,101,682, which can be used in medical applications and includes a surrounding layer of electroplated material covering and bonded to the tube. Another example of a reinforced tubing device is disclosed in U.S. Pat. No. 3,769,813 for a resilient torque tube that is reinforced with alternate layers of wire net and rubber and is useful in vehicle transmissions.
Another important consideration in the design of reinforced tubing devices is the need for adequate tubing resilience (i.e., resistance to permanent deformation, kinking, and buckling under stress). Also, it may be desirable that the reinforced tubing be highly flexible for certain applications, such as for providing a conduit for fluid flow. It may also be desirable that the tubing retain sufficient strength to function effectively as a torque transmitter.
In one application, such as intravascular catheters used to advance medical devices to the arterial system surrounding the heart, there is a need for the catheter to be flexible but nevertheless, also exhibit a certain amount of stiffness so that the catheter may be advanced through various twists and turns presented by the arterial system. Also, while the body of the catheter must exhibit the desired characteristics of flexibility and stiffness, the catheter lumen must have a low friction surface so that an inner catheter or guidewire can be easily advanced through the lumen. An example of one such device which can be used in medical applications and discloses an invention which exhibits the characteristics of flexibility and stiffness is U.S. Pat. No. 5,538,510 which employs coextruded tubular members to achieve the desired results. The disadvantage of this coextrusion invention is that the manufacturing process of this device is complex and has the potential for relatively thick walls and large profiles.
While each of the reinforced tubing devices discussed above can fulfill at least one of the above requirements, there is still a need for a single reinforced tubing device which can be used interchangeably in a variety of applications and which will simultaneously provide all or several of the characteristics mentioned above. To satisfy this need, the present invention recognizes that a reinforced tubing device can be provided which is relatively strong, flexible and thin walled, and which does not easily kink, permanently deform, or buckle under stress.
Accordingly, it is an object of the present invention to provide a thin walled reinforced tubing device which is both relatively flexible and strong.
It is a further object of the present invention to provide a reinforced tubing device that efficiently transmits translational and rotational motion without easily buckling, kinking, or permanently deforming.
Yet another object of the present invention is to provide a reinforced tubing device that yields a specific inner lumen configuration which reduces the overall internal contact area and thereby reduces the frictional drag imparted to objects passing through it.
Another object of the present invention is to provide a method of reinforcing a tubular member which can vary certain properties, such as flexibility, along the length of the tubing.
Another object of the present invention is to provide a method of fabricating flexible tubing from materials not known to have flexible characteristics or from materials with a relatively high modulus.
Another object of the present invention is to provide a tubular structure containing a multitude of protruding elements which, in response to bending or flexing stresses, modify their configuration rather than and thereby minimize significant elongation and compression of the base material.
Yet another object of the present invention is to provide a reinforced tubing with relatively a thin wall and maintaining the characteristics described in the above six paragraphs.
Another object of the present invention is to provide a reinforced tubing device which can be used in a wide variety of applications.
Yet another object of the present invention is to provide a reinforced tubing device that is easy to use and relatively cost effective to manufacture.
For the foregoing reasons, there is a need for a flexible, reinforced and relatively thin walled tubular member that incorporates the features described herewith and that can be inexpensively manufactured.
The present invention is directed to a tubular member that has a continuous annular wall that defines an inner lumen and at least one helical structural member that is embedded within the outer or inner surface of the tube wall. The helical coil or braided structure can be embedded to various depths; within the outer surface or inner surface of the tubular member. It is also an object of the present invention to vary the embedding depth or pitch characteristics of the helical member along any portion of a tubular member to modify the flexibility and torque characteristics over the longitudinal length of the tube. Therefore, the present invention yields a number of ridges or other shaped protrusions projecting into the lumen. These protrusions function to reduce the internal contact area and therefore reduce frictional drag when another structure is being passed through the internal lumen.
One method of manufacturing the present invention includes the steps of engaging a helical member, e.g., a braid or coil, onto the outer surface of the tubular member to form a processing composite tubular member having a first end, a second end, and at least one inner lumen. The tubular member can be either a single or multi-luminal configuration. The processing tubular member is positioned in an appropriately sized heating mold, a system to create a pressure differential is applied between the outer surface of the processing tubular member and the inner lumen by engaging a pressure source to the inner lumen of said tubular member, said processing composite tubular member is then heated to a temperature within a range for a first period of time, while either simultaneously or after a second period of time, a first pressure is applied to said lumen of said composite tubular member for a third period of time, after which said first pressure is reduced to a second pressure, and the composite tubular member is allowed to cool, resulting in a reinforced tubular structure.
Another method of manufacturing the present invention includes the steps of engaging a helical member, e.g., a braid or coil, onto the outer surface of a mandrel and positioning this helical member/mandrel assembly within the inner lumen of the tubular member forming a processing composite assembly, said processing composite assembly is then placed within an appropriately sized heating mold, a system to create a pressure differential is applied between the outer surface and the inner lumen of the tubular member by engaging a vacuum source to the inner lumen of the tubular member and supplying a pressure source to the outer surface of the tubular member or, said processing composite assembly is then heated to a temperature within a range for a first period of time while either simultaneously or after a second period of time, the pressure differential is created by applying a first pressure to the outer surface of the tubular member and a first vacuum to the inner lumen of the tubular member, said pressure differential is applied for a third period of time, after which the pressure differential is reduced to a null, and said composite tubular member allowed to cool, resulting in a processed composite tubular member.
During the fabrication process, the mold can be shaped such that the processed reinforced tubular member is final configured with one or more radii. in addition, the mold can be configured such that the processed reinforced tubular member yields a substantially circular, oval, triangular# or other geometric shape in cross section.
After the reinforced tube is processed, either the outer surface, the inner surface, or both surfaces, can be coated with a suitable material.